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Advanced Imaging Magazine

Updated: January 12th, 2011 10:01 AM CDT

Imaging the Progression of Alzheimer's Disease

Tracking changes in the brain's ventricles may lead to new clues
An example of brain ventricle segmentation.
© Robarts Research Institute
An example of brain ventricle segmentation. The ventricle is essentially a space of fluid in the brain. As tissue around it begins to die, that space increases in size. Research is following the progression of the disease based upon the ventricle size.
A 3D rendering of the segmented lateral ventricles.
© Robarts Research Institute
A 3D rendering of the segmented lateral ventricles.
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By Barry Hochfelder

"As an imaging scientist I want to come up with new ways of imaging the progression of Alzheimer's disease. Magnetic resonance spectroscopy is one method that we study that can measure chemistry in the brain. You can also measure anatomical changes in the brain as a function of time with magnetic resonance imaging (MRI)."

Changes in the brain have been noted for more than 10 years, he explains. Two independent researchers, Nick Fox and Clifford Jack, both demonstrated brain atrophy in Alzheimer's patients in the late 1990s using MRI. Fox imaged patients to establish a baseline, and brought them back repeatedly for up to 30 months and imaged them again to look at anatomical changes over time. Jack showed that the volume of the hippocampus was smaller in patients with Alzheimer's disease compared to control subjects.

Bartha's team, in collaboration with geriatrician Michael Borrie, has zeroed in on changes in the brain ventricles. "I remember going to a conference where it appeared to me that ventricles in the brain changed the most. MRI is particularly good at discriminating between fluid, which fills the ventricles, and surrounding tissue. This means that measurements of ventricle size can be made relatively easily and with high reproducibility."

Much of the expansion of the ventricle may be happening in the part of the ventricle that is next to the entorhinal cortex (EC) and the hippocampus, which are centers of memory formation. The EC forms the main input to the hippocampus and is responsible for preprocessing input signals. The hippocampus (actually, there are two; one on each side of the brain) plays a role in the formation of new memories about experienced events. The EC and hippocampus are among the first areas of the brain to be affected by Alzheimer's disease.

The ventricle is essentially a space of fluid in the brain. As tissue around it begins to die, that space increases in size. The research is following the progression of the disease based upon the ventricle size.



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